Mesoscale Discussion 0135
   NWS Storm Prediction Center Norman OK
   0959 AM CST Sun Feb 28 2021

   Areas affected...northeast Texas through southeast Oklahoma and
   southwest Arkansas

   Concerning...Severe potential...Watch likely 

   Valid 281559Z - 281730Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Thunderstorms are expected to increase in coverage and
   intensity by late morning into the afternoon. Primary threats will
   be isolated large hail and damaging wind gusts, though a tornado or
   two will also be possible. A WW will likely be needed before 17Z.

   DISCUSSION...As of mid morning a cold front extends from eastern OK
   through north central and west central TX. An isolated thunderstorm
   with mid-level updraft rotation has developed on the front and is
   located just east of Gainesville with another isolated storm near
   Mineral Wells. The downstream warm sector is already moderately
   unstable with 1000-1500 J/kg MLCAPE supported by upper 60s F
   dewpoints and 7-7.5 C/km mid-level lapse rates. Further
   destabilization will occur, but will be limited to some degree by
   widespread multi-layer clouds. Weak, progressive impulses embedded
   within the southwesterly upper flow regime and forcing along the
   cold front will contribute to an increase in thunderstorm coverage
   later this morning as the boundary layer slowly warms. The primary
   low-level jet has shifted east of this region resulting in small 0-1
   km hodographs. However, a belt of strong southwesterly winds
   increasing to around 70 kt at 500 mb resides above the warm sector
   and is contributing to 60+ kt effective bulk shear. Therefore, some
   storms should organize with supercells and bowing segments likely,
   eventually consolidating into a dominant linear mode. Large hail and
   isolated damaging wind will be the main threats. The small low-level
   hodographs should tend to limit overall tornado threat. However, a
   tornado or two cannot be ruled out.

   ..Dial/Hart.. 02/28/2021

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...LZK...SHV...TSA...FWD...OUN...

   LAT...LON   32559772 33599665 34899484 34329358 31909679 31859817
               32559772